A stainless steel seamless pipe having high strength and excellent corrosion resistance, and a method for producing the same. The stainless steel seamless pipe has a specified composition and satisfies a predetermined formula. The stainless steel seamless pipe has a microstructure containing at least 30% martensitic phase, at most 60% ferrite phase, and at most 40% retained austenite phase by volume, the stainless steel seamless pipe having a yield strength of 758 MPa or more.

A method for manufacturing a non-oriented electrical steel sheet includes a step of obtaining a hot-rolled steel sheet by performing hot rolling on a steel material having a predetermined chemical composition, a step of performing first cold rolling on the hot-rolled steel sheet, and a step of performing first annealing after the first cold rolling. A final pass of finish rolling is performed in a temperature range equal to or higher than an Ar1 temperature, and cooling of which an average cooling rate is in a range of 50 to 500° C./sec is started in 0.1 sec from completion of rolling of the final pass of the finish rolling and is performed up to a temperature range higher than 250° C. and equal to or lower than 700° C.

A stainless steel pipe of a predetermined composition is provided that comprises N, Ti, Al, V, and Nb so as to satisfy the predetermined formula, the stainless steel pipe having an axial tensile yield strength of 757 MPa or more, an axial compressive yield strength/axial tensile yield strength ratio of 0.85 to 1.15, and a microstructure that is 20 to 80% ferrite phase by volume with the remainder containing an austenite phase, the stainless steel pipe having pipe end portions at least one of which has a fastening portion for an external thread or an internal thread, and having a curvature radius of 0.2 mm or more for a corner R formed by a bottom surface of a thread root and a pressure-side flank surface of the thread, measured in an axial plane section of the fastening portion.

The present invention provides steel sheet having both bendability and hydrogen embrittlement resistance. The steel sheet of the present invention includes a central part of sheet thickness and a surface sort part formed at one side or both sides of the central part of sheet thickness. The microstructure of the central part of sheet thickness comprises, by volume ratio, 60% or more of tempered martensite, respectively less than 30% of ferrite, bainite, pearlite, and retained austenite, and less than 5% of as-quenched martensite. A thickness of the surface soft part is more than 10 μm per side and 15% or less of a thickness of the central part of sheet thickness, an average hardness of the surface soft part is 0.90 time or less of an average hardness of the central part of sheet thickness, the surface soft part includes carbides in a number density of 1×10.sup.4/mm.sup.2 or more, an average particle size of the carbides is 0.250 μm or less, and a standard deviation of a log of a particle size is 0.05 or less.

A hot-dip zinc-plated steel sheet includes a steel sheet, a boundary layer that is provided on a surface of the steel sheet, and a hot-dip zinc-plated layer that is provided on a surface of the boundary layer. In a surface layer region of the steel sheet, an average grain size is 4.0 μm or less and a standard deviation of grain sizes is 2.0 μm or less. In the boundary layer, a maximum Al concentration is 0.30 mass % or more.

This steel sheet for hot stamping includes a base material, an Al-Si alloy plating layer in which the Al content is 75 mass% or more, the Si content is 3 mass% or more and the total of the Al content and the Si content is 95 mass% or more and a Ni plating layer in which the Ni content is more than 90 mass% in this order, the chemical composition of the base material is, by mass%, C: 0.01% or more and less than 0.70%, Si: 0.005% to 1.000%, Mn: 0.40% to 3.00%, Nb: 0.010% to 0.200%, a solid solution of Nb: 0.010% to 0.150%, sol. A1: 0.00020% to 0.50000%, P: 0.100% or less, S: 0.1000% or less, N: 0.0100% or less, Cu: 0% to 1.00%, Ni: 0% to 1.00%, V: 0% to 1.00%, Ti: 0% to 0.150%, Mo: 0% to 1.000%, Cr: 0% to 1.000%, B: 0% to 0.0100%, Ca: 0% to 0.010%. REM: 0% to 0.300%, and a remainder: Fe and an impurity, the Al-Si alloy plating layer has a thickness of 7 to 148 .Math.m, and the Ni plating layer has a thickness of more than 200 nm and 2500 nm or less.

This hot-stamping formed body has a predetermined chemical composition and has a metallographic structure consisting of, by area ratio, a total of 10% to 30% of ferrite and granular bainite and a remainder in microstructure consisting of one or more of martensite, bainite, and tempered martensite, and, in textures of a surface layer region and an inside region, ratios between a pole density of an orientation group consisting of {001}<1-10> to {001}<−1-10> and a pole density of an orientation group consisting of {111}<1-10> to {111}<−1-12> are controlled.

The disclosure refers to a method for preparing NdFeB magnets including at least one of Ce and La. The method includes:

S1) Separately preparing flakes of alloy R1 and flakes of alloy R2 each by a strip casting process, wherein the alloy R1 includes at least one of La and Ce, but the alloy R2 does not include La and Ce;
S2) separately subjecting the flakes of alloy R1 and R2 to a hydrogen embrittlement process followed by pulverizing the process product to alloy powders by jet milling, wherein a ratio of the average particle sizes D50 of the powder of alloy R1 and R2 satisfied formula:

0.32≤R2/R1≤0.66;

S3) mixing the powder of alloy R1 and R2; and
S4) subjecting the mixed powders to molding and magnetic field orientation, cold isostatic pressing, sintering, and an annealing process.

An R-T-B series permanent magnet material, a raw material composition, a preparation method, and an application. The R-T-B series permanent magnet material comprises the following components: R: 29-31.0 wt. %, RH is greater than 1 wt. %, B: 0.905-0.945 wt. %, C: 0.04-0.15 wt. %, N: 0.1-0.4 wt. %, and Fe: 67-69 wt. %, wherein R comprises RL and RH, RL is a light rare earth element, RL comprises Nd, RH is a heavy rare earth element, a (RL.sub.1-yRH.sub.y).sub.2T.sub.17C.sub.x phase is present at the grain boundary of the R-T-B series permanent magnet material, x: 2-3, y: 0.15-0.35, and T must comprise Fe, and also comprises one or more among Co, Ti and N. The permanent magnet material retains relative high Br and Hcj under different heat treatment temperatures.

A high-strength cold-rolled steel sheet having a high yield ratio and excellent stretch flangeability and a method for manufacturing the steel sheet. The high-strength cold-rolled steel sheet has a chemical composition including, by mass %, C: 0.10 to 0.30%, Si: 0.50 to 2.00%, Mn: 2.5 to 4.0%, P: 0.050% or less, S: 0.020% or less, Al: 0.10% or less, N: 0.01% or less, Ti: 0.100% or less, and B: 0.0003 to 0.0030%, with the balance being Fe and incidental impurities. N and Ti satisfy a specified formula, and the total area fraction of martensite and bainite is 95% or more. The number density of bainite grains having an area of 3 μm.sup.2 or more and a carbon concentration of less than 0.7C is 1200 grains/mm.sup.2 or less.